OBJECTIVES: To examine the difference between the Japanese versions of the Health Utilities Index (HUI) Mark2 and the HUI Mark3 scores of patients with Alzheimer’s Disease (AD) in order to undertake the pharmacoeconomic evaluation of AD drugs. METHODS: We conducted a cross-sectional study of AD patients at four sites (three in outpatient and one in institutional settings) using the combined HUI2/HUI3 questionnaire. For those who were not able to make self-evaluations, proxy evaluations were made by caregivers in outpatient settings and by the nursing staff in institutional settings. Severity of dementia was measured by Clinical Dementia Rating (CDR). RESULTS: With the HUI2, the mean (SD) utility scores of the 63 outpatients with mild AD (n=19), moderate AD (n=29), and severe AD (n=12) were 0.61(0.16), 0.50(0.25), 0.38(0.18), respectively. The corresponding scores with HUI3 were 0.33(0.23), 0.17(0.29), and 0.02(0.25), respectively. For inpatient (n=12), it was 0.37(0.21) for those with severe AD (n=10) with the HUI2, and 0.04 (0.20) with the HUI3. The single scores for each attribute of the HUI2 and 3 tended to decrease as the CDR level became more severe. CONCLUSIONS: Compared with the HUI2, the HUI3 yields significantly lower global utility scores for patients with AD. Based on our results, there appears to be a need to further evaluate the validity of the HUI2 and HUI3.